Friday, April 17, 2020

Tracking patient numbers exhibiting symptoms of early Covid-19

Peak patient numbers with Covid-19 symptoms were March 25. "Social distancing" and closing non-essential businesses happened at midnight, March 24. Dang! That was quick. Data from HERE

Percent of patients in Michigan whose primary complaint were symptoms consistent with Covid-19. Specifically, (Fever and/or chills) .AND. (cough, shortness of breath or difficulty breathing)

For age cohorts 18 and older. Younger patients were not included due to their high base-rate and the additional noise they bring.

Recycled graphic. Ignore the red box. Peak cases April 1-through-April 7. In retrospect, the data tracks when the tests came back, not when samples were taken. Data biased by throughput constraints.

Hat/tip to S. Levin

Added later:

I had a question come in via email regarding the symptoms chart.

Consider the 1% of patients (Jan 1-to-Mar 19) as the base-rate. That would include seasonal influenza.

The peak on Mar 25 was about 4 percentage points or 400% above base-rate.

The last four data points are about 1.4 percentage points above base-rate suggesting that the number of new patients is about 1/3 (1.4/4.0) of the peak.

There are a couple of factors that tug in different directions. One is that the number of patients showing up at the doctor's office for maladies that can be deferred dropped. Another factor that may have made March 25 blow-up were worried people going to the doctor early on, just-in-case.

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